1. Field of the Invention
The present invention relates to a hybrid wired and wireless communication system capable of performing both wired communication and wireless communication using a single physical address, and a communication method thereof.
2. Description of the Related Art
Generally, a hybrid wired and wireless communication system includes a central processing unit (CPU), a read-only memory (ROM), a random-access memory (RAM), a peripheral device interface that can be connected to peripheral devices, a wired network interface that can be connected to a wired network, a wireless network interface that can be connected to a wireless network, and protocol modules that can communicate with the wired network interface and the wireless network interface, respectively, all of which communicate across a bus.
To implement networking in a local area network (LAN) using the hybrid system, a network interface card (NIC) is required. The NIC includes a physical device (PHY) that is connected to an actual physical media and can perform transmission/reception of a signal, and a media access control (MAC) module that performs MAC with respect to a medium using the PHY. The MAC module operates based on a physical address used to communicate with another device in a network. A physical address allocated to the NIC is stored in a ROM such as an electrically erasable programmable ROM (EEPROM) or a non-volatile RAM (NVRAM) in a system.
A LAN driver performs packet transmission/reception through a network and is present in an upper layer above the NIC. The LAN driver is connected to a protocol module in an upper protocol layer, which performs packet flow control and packet transfer, via a network driver interface. The NIC includes a wired MAC with associated PHY and a wireless MAC with associated PHY. The protocol layer includes TCP/IP and IPX/SPX protocols. A connection is secured using socket layer for protocols such as HTTP, FTP, and POP 3.
The NIC has a 48-bit fixed physical address, and the protocol module uses a logical address such as an Internet Protocol (IP) address to designate an address. The physical address and the logical address allow the system to be identified in the network. The physical address is stored in an area such as ROM in the system during manufacturing and is transmitted to the MAC module during system initialization.
In an Ethernet frame, a destination physical address indicates a MAC address of a host to receive data. A source physical address indicates a MAC address of a host transmitting the data. Here, in each of the destination and source physical addresses which comprise 48 bits, respectively, if a first bit is 0, the data is unicast (i.e., transmitted to only one receiving host in the network). If the first bit is 1, the data is multicast (i.e., transmitted to only certain hosts in the network). If all of the 48 bits are 1, the data is broadcast to all of hosts in the network. Also included are a frame type and a frame check sequence (FCS).
Before the data is transmitted through the network, an address used in a current layer is embedded into a header of a packet. A receiving party analyzes the address embedded into the header and determines whether the data has been received correctly. If the address embedded into the header is not identical with the receiving party's address, the receiving party does not receive the packet or discards the received packet without processing it.
In a system connected to a network, a packet received via an NIC is transmitted to an application program via a protocol module of a layer bound with the NIC. Data generated in the application program is transmitted to the network via the protocol module and the NIC.
A wireless network interface may be set in an infrastructure mode or an ad-hoc mode. In the ad-hoc mode, a host can communicate with another host wirelessly in a network. In the infrastructure mode, a host can be interlocked with another network via an access point (AP).
Specifically, when a hybrid wired and wireless communication system wirelessly communicates with another communication system through the AP, the wireless communication mode in which the hybrid wired and wireless communication system wirelessly communicates with other types of communication systems not directly but via the AP or the like is referred to as the infrastructure mode. In contrast, when the hybrid wired and wireless communication system wirelessly communicates with the another communication system directly not via the AP, the wireless communication mode is referred to as the ad-hoc mode.
As described above, the hybrid wired and wireless communication system can be simultaneously connected to a wired network and a wireless network by using individual wired and wireless network interfaces. Here, each network interface needs a physical address identifying the network interface in a network. In other words, the hybrid wired and wireless communication system has two or more MAC modules, and two or more physical addresses allocated to the two or more MAC modules, respectively.
To overcome this disadvantage, a hybrid wired and wireless communication system using a single physical address has been introduced. Such hybrid wired and wireless communication system includes individual MAC modules, but stores only one physical address in an associated memory. Further, the system allocates the same physical address to the individual MAC modules. In such a structure, since the individual MAC modules use the same physical address, they are recognized as the same unit by other devices on a network. Accordingly, when the hybrid wired and wireless communication system using a single physical address is connected to a wired network and the wireless network interface operates in the infrastructure mode, a double link is made. Therefore, packet transmission/reception through the wireless network interface is interrupted.
However, when the wireless network interface operates in the ad-hoc mode, packet transmission/reception through the wireless network interface can be performed even though the hybrid wired and wireless communication system is connected to the wired network. While usable, when the hybrid wired and wireless communication system using a single physical address is connected to the wired network and its wireless network interface operates in the ad-hoc mode, a protocol module in an upper layer above the NIC cannot determine a network interface through which a packet will be transmitted. As a result, the hybrid wired and wireless communication system transmits data through both of the wired and wireless network interfaces, and a packet is redundantly transmitted through the wired and wireless networks. Consequently, traffic of one network is loaded onto another network, which causes unnecessary dissipation of a bandwidth.